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+++ b/docs/helios64/maskrom.md
@@ -0,0 +1,106 @@
+Maskrom is special internal firmware of RK3399 that run **Rockusb** driver automatically when there is no 
+bootable firmware found on on-board storage such as SPI flash, eMMC or microSD card.
+
+On Helios64, there are two ways to enter the maskrom mode:
+
+- Disable SPI flash and eMMC according to [Boot Mode Jumper](/helios64/jumper/#boot-mode-p10-p11) and remove microSD card.
+
+- Using [Recovery Button](/helios64/button/#recovery-button)
+
+Rockusb is a vendor specific USB class from Rockchip to download firmware. 
+This USB device has Vendor ID *0x2207* and Product ID *0x330c*.
+
+!!! Info
+    U-Boot has *rockusb* command, but it is not compatible with the Rockchip utilities
+
+## Prerequisites
+
+### RK3399 loader
+
+  In maskrom mode, SoC initiliazed without DRAM and storage support therefore it need *loader* to initialized DRAM and prepare the flashing environment.
+  
+  Download the loader from [here](/helios64/files/maskrom/rk3399_loader_v1.24_RevNocRL.126.bin)
+
+### Windows
+
+#### Rockusb driver
+
+Download and extract *DriverAssistant.zip* from [Rockchip GitHub](https://github.com/rockchip-linux/tools/tree/rk3399/windows).
+
+Run **DriverInstall.exe** under the extracted folder and press **Install Driver**.
+
+!!! Info
+    At this time of writing, the filename is *DriverAssitant_v4.6.zip* and the extracted folder is *DriverAssitant_v4.6*
+
+#### AndroidTools
+
+Download and extract *AndroidTool_Release.zip* from [Rockchip GitHub](https://github.com/rockchip-linux/tools/tree/rk3399/windows).
+
+!!! Info
+    At this time of writing, the filename is *AndroidTool_Release_v2.52.zip*.
+
+### Linux
+
+Download prebuilt rkdevelop from [Rockchip GitHub](https://github.com/rockchip-linux/rkbin/archive/master.zip). 
+Extract the downloaded *rkbin-master.zip* file.
+
+!!! Note
+    You could also compile it from source by following instructions at [Rockchip Wiki](http://opensource.rock-chips.com/wiki_Rkdeveloptool).
+
+## Using Maskrom
+
+**1)** Make sure the system is powered off.
+
+**2)** Put jumper cap to P13 to enable it.
+
+![!Jumper P13](/helios64/img/maskrom/jumper_p13_enabled.jpg)
+
+**3)** Plug in USB type-C cable to Helios64 and the other side to PC.
+
+**4 a)** Disable SPI flash and eMMC according to [Boot Mode Jumper](/helios64/jumper/#boot-mode-p10-p11) and remove microSD card. Power on the system.
+
+ or
+
+**4 b)** Press and hold Recovery button. Power on the system and release recovery button after System Status LED blink twice. 
+
+### Under Windows
+
+**1.** Open Device Manager and verify whether rockusb device is recognized.
+
+![rockusb on Device Manager](/helios64/img/maskrom/rockusb_device.png)
+
+**2.** Run **AndroidTool.exe** and check whether there is **Found One MASKROM Device**.
+
+![!AndroidTool Main Window](/helios64/img/maskrom/androidtools_00_main.png)
+
+**3.** Press button to load and select following files,
+
+- Loader = rk3399_loader_v1.24_RevNocRL.126.bin
+
+- Image = OS image to write
+
+!!! Warning
+    The image must be Raw image, not in compressed form.
+
+![!AndroidTool Files loaded](/helios64/img/maskrom/androidtools_01_ready_to_download.png)
+
+**4.** Checklist both row and press **Run** button. Observer the log textbox.
+
+![!AndroidTool Writing Images](/helios64/img/maskrom/androidtools_02_download_in_progress.png)
+
+**5.** The log textbox will show **Download image OK** when finished and system will automatically reboot.
+
+![!AndroidTool Writing Images](/helios64/img/maskrom/androidtools_03_done.png)
+
+**6.** Remove jumper on P13, you should have USB Serial connected to your PC.
+
+**7.** Continue to setup the OS through Serial Console.
+
+
+## References
+
+[Rkdeveloptool - Rockchip Open Source Document](http://opensource.rock-chips.com/wiki_Rkdeveloptool)
+
+[Rockusb - Rockchip Open Source Document](http://opensource.rock-chips.com/wiki_Rockusb)
+
+
diff --git a/mkdocs.yml b/mkdocs.yml
index acadb43..c0f9fe1 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -90,6 +90,7 @@ nav:
     - Jumper: 'helios64/jumper.md'
     - LED: 'helios64/led.md'
     - M.2: 'helios64/m2.md'
+    - Maskrom: 'helios64/maskrom.md'
     - PMIC: 'helios64/pmic.md'
     - PWM Fan: 'helios64/pwm.md'
     - RTC: 'helios64/rtc.md'